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authorUwe Kleine-König <u.kleine-koenig@pengutronix.de>2020-01-21 10:17:02 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-01-22 12:22:31 +0300
commit101aa46bd221b768dfff8ef3745173fc8dbb85ee (patch)
treeb5f56b03ed8669053ed21b23ef38556365412e46 /drivers/tty
parent48d414a3f2ecd995b65e52df3f8d6b5d0e8d026b (diff)
downloadlinux-101aa46bd221b768dfff8ef3745173fc8dbb85ee.tar.xz
serial: imx: fix a race condition in receive path
The main irq handler function starts by first masking disabled interrupts in the status register values to ensure to only handle enabled interrupts. This is important as when the RX path in the hardware is disabled reading the RX fifo results in an external abort. This checking must be done under the port lock, otherwise the following can happen: CPU1 | CPU2 | irq triggers as there are chars | in the RX fifo | | grab port lock imx_uart_int finds RRDY enabled | and calls imx_uart_rxint which | has to wait for port lock | | disable RX (e.g. because we're | using RS485 with !RX_DURING_TX) | | release port lock read from RX fifo with RX | disabled => exception | So take the port lock only once in imx_uart_int() instead of in the functions called from there. Reported-by: Andre Renaud <arenaud@designa-electronics.com> Cc: stable@vger.kernel.org Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Link: https://lore.kernel.org/r/20200121071702.20150-1-u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/imx.c51
1 files changed, 38 insertions, 13 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 83c6e2ac0e8d..0c6c63166250 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -696,22 +696,33 @@ static void imx_uart_start_tx(struct uart_port *port)
}
}
-static irqreturn_t imx_uart_rtsint(int irq, void *dev_id)
+static irqreturn_t __imx_uart_rtsint(int irq, void *dev_id)
{
struct imx_port *sport = dev_id;
u32 usr1;
- spin_lock(&sport->port.lock);
-
imx_uart_writel(sport, USR1_RTSD, USR1);
usr1 = imx_uart_readl(sport, USR1) & USR1_RTSS;
uart_handle_cts_change(&sport->port, !!usr1);
wake_up_interruptible(&sport->port.state->port.delta_msr_wait);
- spin_unlock(&sport->port.lock);
return IRQ_HANDLED;
}
+static irqreturn_t imx_uart_rtsint(int irq, void *dev_id)
+{
+ struct imx_port *sport = dev_id;
+ irqreturn_t ret;
+
+ spin_lock(&sport->port.lock);
+
+ ret = __imx_uart_rtsint(irq, dev_id);
+
+ spin_unlock(&sport->port.lock);
+
+ return ret;
+}
+
static irqreturn_t imx_uart_txint(int irq, void *dev_id)
{
struct imx_port *sport = dev_id;
@@ -722,14 +733,12 @@ static irqreturn_t imx_uart_txint(int irq, void *dev_id)
return IRQ_HANDLED;
}
-static irqreturn_t imx_uart_rxint(int irq, void *dev_id)
+static irqreturn_t __imx_uart_rxint(int irq, void *dev_id)
{
struct imx_port *sport = dev_id;
unsigned int rx, flg, ignored = 0;
struct tty_port *port = &sport->port.state->port;
- spin_lock(&sport->port.lock);
-
while (imx_uart_readl(sport, USR2) & USR2_RDR) {
u32 usr2;
@@ -786,11 +795,25 @@ static irqreturn_t imx_uart_rxint(int irq, void *dev_id)
}
out:
- spin_unlock(&sport->port.lock);
tty_flip_buffer_push(port);
+
return IRQ_HANDLED;
}
+static irqreturn_t imx_uart_rxint(int irq, void *dev_id)
+{
+ struct imx_port *sport = dev_id;
+ irqreturn_t ret;
+
+ spin_lock(&sport->port.lock);
+
+ ret = __imx_uart_rxint(irq, dev_id);
+
+ spin_unlock(&sport->port.lock);
+
+ return ret;
+}
+
static void imx_uart_clear_rx_errors(struct imx_port *sport);
/*
@@ -849,6 +872,8 @@ static irqreturn_t imx_uart_int(int irq, void *dev_id)
unsigned int usr1, usr2, ucr1, ucr2, ucr3, ucr4;
irqreturn_t ret = IRQ_NONE;
+ spin_lock(&sport->port.lock);
+
usr1 = imx_uart_readl(sport, USR1);
usr2 = imx_uart_readl(sport, USR2);
ucr1 = imx_uart_readl(sport, UCR1);
@@ -882,27 +907,25 @@ static irqreturn_t imx_uart_int(int irq, void *dev_id)
usr2 &= ~USR2_ORE;
if (usr1 & (USR1_RRDY | USR1_AGTIM)) {
- imx_uart_rxint(irq, dev_id);
+ __imx_uart_rxint(irq, dev_id);
ret = IRQ_HANDLED;
}
if ((usr1 & USR1_TRDY) || (usr2 & USR2_TXDC)) {
- imx_uart_txint(irq, dev_id);
+ imx_uart_transmit_buffer(sport);
ret = IRQ_HANDLED;
}
if (usr1 & USR1_DTRD) {
imx_uart_writel(sport, USR1_DTRD, USR1);
- spin_lock(&sport->port.lock);
imx_uart_mctrl_check(sport);
- spin_unlock(&sport->port.lock);
ret = IRQ_HANDLED;
}
if (usr1 & USR1_RTSD) {
- imx_uart_rtsint(irq, dev_id);
+ __imx_uart_rtsint(irq, dev_id);
ret = IRQ_HANDLED;
}
@@ -917,6 +940,8 @@ static irqreturn_t imx_uart_int(int irq, void *dev_id)
ret = IRQ_HANDLED;
}
+ spin_unlock(&sport->port.lock);
+
return ret;
}